Gdz Biologiia 7 Sumatokhin Klass Dvukhstvorchatye Molliuski Onlain Apr 2026

: Unlike gastropods (snails), bivalves lack a distinct head. Their body consists of a torso and a muscular "foot" used for burrowing or anchoring.

: They possess an open circulatory system with a heart and vessels. : Unlike gastropods (snails), bivalves lack a distinct head

: The body is laterally compressed and enclosed in a bilateral shell. This shell consists of three layers: an outer organic layer (periostracum), a middle calcareous layer, and an inner pearly layer (nacre). : The body is laterally compressed and enclosed

: They breathe through plate-like gills (ctenidia) located in the mantle cavity. For further study and visual aids, students can

For further study and visual aids, students can refer to educational platforms like Yaklass or watch lesson summaries on YouTube .

: By filtering vast amounts of water, bivalves like mussels and oysters act as natural water purifiers in ecosystems.